B cell toll-like receptors with respect to the pathogenesis of Sjögren's syndrome.

Sjögren's syndrome (SS) is a chronic autoimmune immunopathological disease of unknown aetiology. It is characterized by focal lymphocyte infiltration and inflammation in exocrinne glands, involving especially salivary and lacrimal glands. Hypofunction of the glands leads to the decreased glandular secretion together with impaired production of saliva and tears, resulting in dryness of the mouth and eyes (xerostomia and xerophthalmia, respectively). Some of the studies have suggested that Toll-like receptors and B cells play a pivotal role in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis and SS etc. Stimulation of B cells via the TLRs pathway leads to several important changes including increase in antibody production, differentiation to plasma cells, cytokine production and up-regulation of molecules essential for antigen presentation to (autoreactive) T cells. Experimental data support the idea that co-engagement of BCR and TLR might be sufficient for B cell activation and lead to the failure of tolerance. In human naive B cells, most TLRs are expressed at very low or undetectable level, but expression of TLR 7 and 9 is rapidly induced by B cell receptor triggering. This review will focus on the possible role of B cells and TLRs signaling in the pathogenesis of SS.